Podcast
Questions and Answers
In an electrochemical process, what role do redox reactions play?
In an electrochemical process, what role do redox reactions play?
- They inhibit the flow of electrons, preventing energy conversion.
- They facilitate the transfer of electrons, enabling energy conversion and chemical changes. (correct)
- They maintain a constant voltage, ensuring reactions proceed without energy input.
- They convert electrical energy directly into thermal energy.
What occurs during oxidation?
What occurs during oxidation?
- The oxidation number decreases, functioning as the oxidizing agent.
- The substance gains electrons.
- The oxidation number increases, functioning as the reducing agent. (correct)
- The oxidation number remains constant.
In an electrolytic cell, how are electrons directed to move in a non-spontaneous direction?
In an electrolytic cell, how are electrons directed to move in a non-spontaneous direction?
- By increasing the temperature to provide the necessary kinetic energy.
- Through the concentration gradient between the electrodes.
- Through the use of a catalyst that lowers the activation energy.
- By applying an external voltage to force the electron flow. (correct)
Which of the following best describes the function of a galvanic cell?
Which of the following best describes the function of a galvanic cell?
How does the energy flow differ between galvanic and electrolytic cells?
How does the energy flow differ between galvanic and electrolytic cells?
At which electrode does oxidation occur in a galvanic cell, and what is its charge?
At which electrode does oxidation occur in a galvanic cell, and what is its charge?
How do electrons flow in a galvanic cell?
How do electrons flow in a galvanic cell?
What is the role of the salt bridge in a galvanic cell?
What is the role of the salt bridge in a galvanic cell?
In the Daniell cell (Zn-Cu cell), what happens at the anode?
In the Daniell cell (Zn-Cu cell), what happens at the anode?
Which of the following is a characteristic of electrolytic cells but not of galvanic cells?
Which of the following is a characteristic of electrolytic cells but not of galvanic cells?
During the discharge of a battery, what process occurs at the anode?
During the discharge of a battery, what process occurs at the anode?
Which of the following is true regarding the movement of electrons within a battery that is powering a device?
Which of the following is true regarding the movement of electrons within a battery that is powering a device?
What is the key characteristic of a primary battery?
What is the key characteristic of a primary battery?
What is the main difference between a mineral and an ore?
What is the main difference between a mineral and an ore?
Which of the following best describes the structure of a crystal?
Which of the following best describes the structure of a crystal?
What type of materials are separated during the flotation process?
What type of materials are separated during the flotation process?
During the flotation process, what makes the valuable minerals hydrophobic?
During the flotation process, what makes the valuable minerals hydrophobic?
What role do frothers play in the flotation process?
What role do frothers play in the flotation process?
What happens to CaCO3 when it undergoes thermal decomposition?
What happens to CaCO3 when it undergoes thermal decomposition?
In the process of obtaining iron from iron ore via smelting, what is the role of coke?
In the process of obtaining iron from iron ore via smelting, what is the role of coke?
Flashcards
What are Redox Reactions?
What are Redox Reactions?
Reactions where electrons are transferred between chemical species.
What is an Electrochemical Process?
What is an Electrochemical Process?
A reaction where energy is released spontaneously and converted to electricity.
What is Oxidation?
What is Oxidation?
The increase in oxidation number; involves losing electrons.
What is Reduction?
What is Reduction?
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What is Oxidation Number?
What is Oxidation Number?
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What is a Galvanic Cell?
What is a Galvanic Cell?
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What is an Electrolytic Cell?
What is an Electrolytic Cell?
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What is the Anode?
What is the Anode?
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What is the Cathode?
What is the Cathode?
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What is a Salt Bridge?
What is a Salt Bridge?
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What is a Primary battery?
What is a Primary battery?
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What is a Secondary Battery?
What is a Secondary Battery?
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What is a Mineral?
What is a Mineral?
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What is an Ore?
What is an Ore?
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What is an Alloy?
What is an Alloy?
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What is an Amalgam?
What is an Amalgam?
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What is a Unit Cell?
What is a Unit Cell?
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What is a Crystal?
What is a Crystal?
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What is an Amorphous Solid?
What is an Amorphous Solid?
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What is Flotation?
What is Flotation?
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Study Notes
- Electrochemistry involves redox reactions
- Redox reactions involve oxidation and reduction.
Electrochemical Processes
- Oxidation-reduction reactions release energy from spontaneous reactions, converting it into electricity.
- Electrical energy can drive non-spontaneous reactions.
Oxidation
- The oxidation number increases
- Oxidation is the reducing agent
Reduction
- The oxidation number decreases
- Reduction is the oxidizing agent
Role of Electrons
- Electrons lost in oxidation are gained in reduction
- This maintains charge balance in the reaction.
- Electron movement occurs through an external circuit in galvanic cells
- This generates electric current.
- In electrolytic cells, external voltage forces electrons to move non-spontaneously, driving a chemical reaction.
Oxidation Number
- Oxidation number represents the number of electrons an atom can gain, lose, or share.
- Uncombined and free elements have an oxidation number of zero.
- For simple ions, the oxidation number equals the charge.
- Oxygen usually has an oxidation number of -2.
- Hydrogen usually has an oxidation number of +1.
- Oxidation numbers must be consistent with the overall charge of the molecule.
- Fractional oxidation numbers are possible.
Galvanic Cell vs Electrolytic Cell
| Feature | Galvanic Cell | Electrolytic Cell |
|---|---|---|
| Function | Converts chemical energy into electrical energy | Converts electrical energy into chemical energy |
| (spontaneous reaction) | (non-spontaneous reaction) | |
| Energy Flow | Electrons move from anode to cathode via external circuit | External power source forces electrons against natural direction |
| Reaction Type | Spontaneous redox reaction (ΔG0) | |
| Electrode Charge | Anode (-), Cathode (+) | Anode (+), Cathode (-) |
| Electron Flow | Anode to cathode via external circuit | External power source forces electrons from cathode to anode |
| Example | Daniell Cell (Zinc is oxidized, copper reduced) | Electrolysis of Water (splitting water with electricity) |
| Applications | Batteries, fuel cells | Electroplating, electrolysis (e.g., aluminum from bauxite) |
Galvanic Cell Details
- Converts chemical energy into electrical energy through spontaneous redox reactions.
- Energy Conversion: Transforms chemical energy into electrical energy.
- Reaction Type: Uses spontaneous redox reactions.
- External Energy: Does not need an external energy source to function.
- Examples: Includes batteries and fuel cells.
- Anode: Negative electrode
- Cathode: Positive electrode
Electrolytic Cell Details
- Change electrical energy by forcing non-spontaneous reactions.
- Energy Conversion: Transforms electrical energy into chemical energy.
- Reaction Type: Drives non-spontaneous redox reactions.
- External Energy: Requires an external energy source.
- Examples: Includes electrolysis of water and electroplating.
- Anode: Positive electrode
- Cathode: Negative electrode
Galvanic Cell Diagram Components
- Anode (Zinc): Oxidation
- Zn → Zn²⁺ + 2e⁻
- Cathode (Copper): Reduction
- Cu²⁺ + 2e⁻ → Cu
- Salt Bridge (KNO₃ or KCl): Maintains charge balance.
- Anions move toward the anode.
- Cations move toward the cathode.
- Electrolyte Solutions (ZnSO₄ and CuSO₄)
- ZnSO₄ provides Zn²⁺ ions.
- CuSO₄ provides Cu²⁺ ions.
Working Principle
- Electron Flow: Zn (anode) → External Circuit → Cu (cathode)
- Ion Flow (Salt Bridge):
- Negative ions move to anode (-).
- Positive ions move to cathode (+).
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